Insulator



May 26, 1931.

R. B. HESSON INSULATOR Filed May 17, 1928 4 gwuento;

i rPatented May 26, 1931 UNITED STATES ROBERT B. HESSON, vOIE' MIDDLESEX BOROUGH, NEW JERSEY, ASSIGNOR TO RESEARCH PATENT o1-FICE y CORPORATION, F NEW YORK, N. .Y., A CORPORATION 0l' NEW YORK INSULATOB application mea my 17, 192s. serial zo. $78,471:.

This invention relates to'improvements in insulators, and more particularly to insulators which, due to their construction or place of use, are subject to damage or destruction s arising from deposits thereon of conductive material.

In electrical precipitators for the removal of tar and light oils from gas the problem of maintaining the insulators vin working l 1o condition has caused considerable trouble,

due to the fact that deposits of tar, oil, water and the like on the insulators results in a `conductive surface between the discharge electrode system and the ground. The insulators are damaged byburning or may`be` destroyed by the flash-over or arcing conduction which takes place when the conductive deposit is formed. As the insulators provide the mechanical support for the discharge electrode system the replacementof a broken or damaged insulator requires con.- siderable time as it is usually necessary to readj ust the discharge electrodes with respect to the collecting electrodes. The actual cost of the insulators is also a material item in the i operating expenses.

An object of the invention is to provide an insulator which is enclosed within a sub- A stantially air-tighthousing, the housing being formed, in part at least, of insulating material.

A further object of this invention is to provide an insulator construction, including a relatively inexpensive and easily renewable insulating surface which protects the main l insulator from deposits of conductive material.

A further object is to' provide an auxiliary insulating surface in parallel with and form- 40 in a protective housing for the main insu ator.

More specifically, an object. of the invention is to provide an electrical precipitator in which the insulators which carry the discharge electrodes are protected by an aux# iliary insulating surface formed of relatively inexpensive material, thereby preventing the deposition of conductive material upon the insulators. These and other objects of the invention will be apparent from the following specification, when taken with the accompanying drawings, in which:

Fig. 1 is a fragmentary side view, partially in section, through a portion of an electrical precipitator, Y

Fig. 2 is a vertical section through a ped estal insulator embodying the invention,

Fig. 3iis a side elevation of a strain in- 'sulator provided with a protective covering, an

further modification ofthe invention.

In the drawings the numeral 1 indicates a ortion of the treater chamber of an electrical precipitator having discharge electrodes 2 and collecting electrodes 3 mounted therein. The discharge electrodes 2 are carried by a beam 4 which extends through the wall ofthe treater chamber and into the insulator compartment 5. The beam 4 is supported by the insulator 6 which is in turn supported by the bottom wall 5 of insulator compartment 5 which is part of the grounded structure of the precipitator. A hollow insulator 6 serves to separate this grounded part ofthe precipitator from the high voltage frame work supporting the discharge electrodes and the voltage drop along its surface from top to bottom i's the voltage, above ground, which is impressed on the discharge electrode system. The beam 4 is connected to a high voltage current supply (not shown) by a conductor 7 which extends through the insulator and is insulated from the bottom wall 5 of the insulator compartment by an insulating bushing 6.

The insulator chamber 5 is provided with a jacket 8 of heat insulating material, and a steam pipe 9 is provided for heating the insulator chamber. 'Bhe ,outer wall fof the chamber 5 isprovidedlwith a man-hole having a cover plate 10 which permits access to the interiorl of the chamber. i

By thus heating the space within the insulator chamber the deposition of moisture, oil

and tar may be reduced or substantially eliminated. To prevent damage to the insulator through the inadvertent stoppage of the steam supply the insulator 6 is provided with Fig. 4: is asectional view illustrating a a substantially air-tight housin or cover which is formed, in part at least, o? insulating material, since thecover is subjected to the same potential difference as the insulator. As shown in Fig. 1, the usual flanged hood l1 is provided with a second flange 12 which is positioned Within and extends below the outer rim of the hood.v A cylindrical shell 13 of insulating material is secured to the depending flange 12 by a fastening band 14, such as a clamping ring, a wrapping-of cord, wire or the like, and the lower end of the shell 13 I is fixed to the flange 15 .of the insulator 6 by a similar band, cord or wire 15. The

shell 13 provides a substantially air-tightV housing for the insulator 6 and prevents theV deposit thereon of conductive material. u

The shell or auxiliary insulator may be formed of any suitableinsulatino material, such as, for example, waxed or oiled paper, impregnated wood, cambric, glass or vitreous material, &c. The end s of the shell are,

.of course, at the same potentials as the. ad-

jacent ends ofthe insulators 6-and by analogy to the similar arrangement of electrical conductors, the insulatorsmay be said to be arranged in parallel. Thev auxiliary insulating surface will receive the ldeposits that otherwise would have formed on the insulator 6, and any leakage across the same willl be indicated by a current flow greatly above that required for normal operation. When this condition exists the man-hole cover 10 is removed and the damaged insulating shell 13 is replaced. The voperation isv an exceedingly simple one, since no change orreadjustment of the discharge electrode system is necessary.

The invention is particularly useful in con nection with an electrical precipitator but may be applied to any insulators which are subject todamage arising from the depositionof conductive material.

As shown in 2, a pedestal type of in- 'sulator 16 is rovided with an auxiliaryv insulating sur ace 17 whichL is secured to flanged disks 18 at the ends of the insulator I by means of bands or wires 20. The upper disk.1.8 is provided with a depending flange 18 whlch is of larger diameter than the insulating surface 17 and protects the latterv froml any moisture or other condensate collectmg upon the structure above the pedestal insulator.

As shown in'Fig. 3, the invention may be applled to a st-rain insulator of the type made up lfrom a plurality of unit insulators 21, the

insulating surface 22 being fixed todisks 23 -Which are carried by the end -units of. the

string of insulators.

As shown in Fig. 4, the insulator `l24is lo# cated within a drum or cylindrical container 25, which may be'formed either of 'nonductive or insulating material, depending uponthe conditions encountered' at the place of use of the insulator assembly. The upper end of the insulator is provided with a flanged disk 26 and a sheet of insulating material 27 is fixed to the disk 26 and the upper portion of the drum 25 'to forman air-tlght closure for the drum.

. If desired, the embodiment shown in Fig. 4 may be modified b omitting the sheet of insulating material 27 and completely filling the drum 25 with insulating material of a nature similar to or comprising gypsum, fine sand, kieselguhr or other siliceousl material. This `insulating material should extend to the top of the insulator and the top of drum 25.

vIn this modification anyconductive material in the zone of the insulator will deposit on or be absorbed by the filling material atits exposed top surface and will not affect the insulator. Consequently, any electrical leakage Ywill be through the insulating material and not over the porcelain insulator surface.

pensive than the principal insulator. For

Should a break down occur, the insulation of f `auxiliary insulating surface were more Vexthis reason the term relatively inexpensive as employed in this specification and the'fol-v lowing claims is notl used to identify auxiliaryinsulator constructions which are necessarily less expensive than theprincipal insulators which they protect. As a general rule, however, the auxiliary insulating surfaces will be provided by textile or other cellulosic materials which are much less expensive than the ceramic insulators which they protect fromdamage and destruction.

The specific embodiments which have been j described above are illustrative of thewide application of the invention and it is to be understood that material changes may be vmade in the several parts, their relative size, shape and-arrangement without departure from my invention as set forth in the following'- claims. I claim:

1. The combination with an insulator, disks arranged at the ends of said insulator, and a. sheet of insulating material cooperating with said disks and spaced from-said insulator to .I

form afsubstantially air-tight housing for said insulator.

2. The combination with an electrical insulator, of a housing` preventing the deposition of conductive material upon said insulator,

. the ends of said housing being secured to and subjected to the electrical potentials'at the respective ends of said insulator, anda portion of said housing beingl formed of-relatively inexpensive insulating material spaced from said insulator to provide a chamber surrounding the same.

3. In an electrical precipitator for removing tar and the like from gases, a treater chamber having discharge and collecting electrode lsystems therein, an insulator compartment communicating with said chamber,

an insulator Within said compartment and providing a support for said discharge electrode system, and. a second insulator sur` rounding said supporting insulator and providing a substantially the same, said second insulator being formed of relatively inexpensive material.

4. The combination With an electrical insulator, of a substantially air-tight housing enclosing said insulator to prevent the deposition of conductin material thereon, said housing havingy portions thereof connected to and at the electrical potentials of the respective ends of said insulator, and having another portion thereof formed of an insulating materlal havinga low mechanical strength.

` 5. In an electrical precipitator; the combination with a discharge electrode, and an insulator providing a support therefor, of a gas-tight' housing enclosing said insulator, said housing comprlsing insulatmg material in parallel with the said insulator. the combination with a 6. In an insulator, rigid body of insulating material having rigid connecting means at the respective ends thereof, of insulating material removablydisposed around said rigid body and connected to the respective connecting means to provide an air-tight enclosure for said rigid body and a non-conductive path in parallel air-tight enclosure forl 

